Question

I have created an array, two dictionaries and a tableview. The tableview should display the contents of array and that array contains the data of dictionaries. When i try to display it using “[mArray addObject:(mDictionary)];” its throwing an exception but if i use “[mArray addObject:[mDictionary objectForKey:@”firstname”]];” its working fine.

Can you help me to understand why is it happening and isn’t it possible to display the dictionary value without using “objectForKey”?

Here is my “ViewController.m”.

#import "ViewController.h"

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
    mArray = [[NSMutableArray alloc]init];
    mDictionary = [[NSMutableDictionary alloc]init];
    [mDictionary setValue:@"shanu" forKey:@"firstname"];
    [mDictionary setValue:@"kumar" forKey:@"lastname"];
    mDictionary2 = [[NSMutableDictionary alloc]init];
    [mDictionary2 setValue:@"hgjghjgf" forKey:@"firstname1"];
    [mDictionary2 setValue:@"ghjgjgfj" forKey:@"lastname1"];
    [mArray addObject:mDictionary];
    [mArray addObject:mDictionary2];

    CGRect frame = self.view.frame;
    UITableView *tableView = [[UITableView alloc]initWithFrame:frame style:UITableViewStylePlain];
    tableView.separatorStyle = UITableViewCellSeparatorStyleSingleLine;
    tableView.backgroundColor = [UIColor cyanColor];
    tableView.separatorColor = [UIColor blackColor];
    tableView.delegate = self;
    tableView.dataSource = self;
    [self.view addSubview:tableView];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return @"Array and Tableview";
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{

    return mArray.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }
    cell.textLabel.text = [mArray objectAtIndex:indexPath.row];
    return cell;
}

- (void)dealloc
{
    [mArray release];
    [mDictionary release];
    [mDictionary2 release];
    [super dealloc];
}
@end

Answer 1

If you try to assign the some text to the cell’s textlabel the object returned from:

[mArray objectAtIndex:indexPath.row];

should be a string and not a whole dictionary.

When you just put the whole dictionary in the array [mArray objectAtIndex:indexPath.row]; will return a dictionary and you cannot assign a dictionary to the textlabel so you get an exception. If you want to store the whole dictionary use objectForKey to get the string you want:

cell.textLabel.text = [[mArray objectAtIndex:indexPath.row] objectForKey:@"WHAT_EVER_KEY_YOU_WANT"];

---

btw, you are not using ARC zo you probably want to get an autoreleased UITableViewCell so add autorelease to you cell:

cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"] autorelease];

or

cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
[cell autorelease];